1. Field of the Invention
The present disclosure generally relates to devices for and methods of protecting an active material actuator against overload conditions; and more particularly, to a device for and method of overload protection that lacks an automatic reset in accomplishing the same.
2. Discussion of Prior Art
Active material actuators, such as shape memory alloy (SMA) wires, are generally protected from mechanical overload by the use of mechanical springs or electrical/controls schemes to avoid damage to the actuators when the output load exceeds a recommended limit. To service the actuator over its life, these measures often feature automatic resets that present various concerns in the art. Most notably, it is appreciated that the added functionality of automatic resets increase the complexity, packaging space, and costs associated with overload protection, and with respect to springs, present an increasing biasing force that must be overcome by the actuator. Moreover, as a result of automatic resets, overload events may go undetected, thereby exposing the actuator and driven mechanism to a continuous condition. More simplistic non-automatically resetting overload protection mechanisms have been developed, including end crimps designed to release an SMA wire when the load exceeds a specified level; however, these mechanisms also present concerns. For example, where releasable crimps are used, it is appreciated that wire damage may occur as the wire is stripped from the crimp.